Process for preparing dihalovinylcyclopropanecarboxylates

Abstract

A cyclopropanecarboxylate of the formula ##STR1## is prepared by the reaction of a compound of the formula ##STR2## with an alkoxide in an ether type solvent. R 1 , R 2 , and R 4 each independently is hydrogen or a hydrocarbon residue, R 3 is an alcohol residue, X is halogen, and A is --CH 2 --CX 3 or --CH═CX 2 .

We claim: 
     
       1. A process for preparing a dihalovinylcyclopropanecarboxylate represented by the formula ##STR8## wherein R 1  and R 2  each independently represent a hydrogen atom or a hydrocarbon group; R 3  represents a lower alkyl group or a group of the formula ##STR9## wherein Y represents an oxygen atom, a sulfur atom or a --CH═CH-- group, R 5  represents a hydrogen atom or a cyano group, R 6  represents a hydrogen atom, a lower alkyl group, a phenoxy group, a benzyl group or a thiophenyl group, and R 7  represents a hydrogen atom or a lower alkyl group; and X represents a halogen atom; which comprises reacting a compound represented by the formula ##STR10## wherein R 1 , R 2 , R 3 , and X are as defined above, and X' is a halogen of atomic number equal to or lower than X, and R 4  represents a hydrogen atom, a lower alkyl group or a phenyl group, with an alkali metal alkoxide in an ether type solvent. 
     
     
       2. A process of claim 1 in which R 1 , R 2 , and R 4  each independently is hydrogen, lower alkyl, or phenyl, R 3  is lower alkyl, 3-phenoxybenzyl, α-cyano-3-phenoxybenzyl, or 5-benzyl-3-furylmethyl, X is chlorine, bromine or fluorine, and X' is chlorine or bromine. 
     
     
       3. The process of claim 2 in which R 1 , R 2 , and R 4  each is methyl. 
     
     
       4. The process of claim 3 in which X and X' each is chlorine. 
     
     
       5. The process of claim 3 in which R 3  is lower alkyl. 
     
     
       6. The process of claim 1 in which the compound of formula (II) is prepared by adding a carbon tetrahalide to an α-acyl-γ-unsaturated carboxylate represented by the formula ##STR11## in the presence of a copper or iron salt and an organic amine. 
     
     
       7. The process of claim 6 in which the carbon tetrahalide is carbon tetrachloride, carbon tetrabromide, or bromotrichloromethane, R 1 , R 2 , and R 4  each is methyl, and R 3  is lower alkyl. 
     
     
       8. Process as in claim 1 in which the amount of base is in excess of 2 mol equivalents. 
     
     
       9. Process as in claim 1 in which the amount of base is at least 3 mol equivalents. 
     
     
       10. Process as in claim 9 in which said solvent is tetrahydrofuran. 
     
     
       11. Process as in claim 10 in which said alkali metal alkoxide is sodium ethoxide. 
     
     
       12. Process as in claim 10 in which said alkali metal alkoxide is sodium methoxide. 
     
     
       13. Process as in claim 8 in which R 1 , R 2 , and R 4  are each methyl, X 1  and X are each chlorine and R is lower alkyl. 
     
     
       14. Process as in claim 13 in which the amount of base is at least 3 mol equivalents and the solvent is tetrahydrofuran. 
     
     
       15. A process for preparing a dihalovinylcyclopropanecarboxylate represented by the formula ##STR12## where R 1  and R 2  each independently represents a hydrogen atom or a hydrocarbon residual group; R 3  represents a lower alkyl group or a group of the formula ##STR13## wherein Y represents an oxygen atom, a sulfur atom or a --CH═CH-- group, R 5  represents a hydrogen atom or a cyano group, R 6  represents a hydrogen atom, a lower alkyl group, a phenoxy group, a benzyl group or a thiophenyl group, and R 7  represents a hydrogen atom or a lower alkyl group; and X represents a halogen atom; which comprises reacting a compound represented by the formula ##STR14## wherein R 1 , R 2 , R 3 , and X are as defined above, and R 4  represents a hydrogen atom, a lower alkyl group or a phenyl group, with an alkali metal alkoxide in an ether type solvent. 
     
     
       16. Process as in claim 15 in which the amount of base is in excess of 2 mol equivalents. 
     
     
       17. Process as in claim 16 in which said solvent is tetrahydrofuran.